This invention relates generally to liquid heaters, as for example water heaters, and more particularly concerns improvements in heaters wherein heat exchangers receive heat from hot products of combustion.
A constant problem associated with the operation of such heaters is that of unwanted condensation of moisture formed by the combustion process. Such condensation typically occurs on the heat exchanger tubes or fins due to their cooling by the liquid or water flowing in the tubes. To prevent such condensation, the liquid flow rate must be reduced to objectionably low level and the flue gas must be kept at objectionably high temperatures, all of which reduces operating efficiencies, and causes liming of tubes, and heat exchanger burn-out. Other problems have to do with difficulties in obtaining efficient housing and header design.